In the area of anti-skid chains, which usually consist of chain links arranged in the form of a chain mesh, different profiles are used in the chain links. The following embodiments refer primarily to conventional straight chain links with an oval shape. Straight chain links are defined here as those whose side walls lie with a longitudinal central axis in one plane.
One profile that is frequently represented on the market is the round link chain, in which the chain links have a round cross section. Furthermore, square chains, whose chain links have essentially a rectangular or square profile, are found in the state of the art.
The most frequently used profile in chains is the special square chain, whose chain links have a square profile on the outside and are designed with a round profile on the inside. “On the outside” is defined here as the outwardly directed area of the chain links, while “on the inside” is designated as the inner area, i.e., almost the interior of the oval of the chain link (or the eye of the chain link).
The chain types mentioned are additionally designed with parts subject to wear such as stubs, spikes or straps for increasing the lifetime and anti-skid effectiveness. Consequently, on the one hand, the lifetime is increased, because the load of the chain links is partly rolled over onto the parts subject to wear. On the other hand, thanks to the thus enhanced anti-skid chain, the adhesiveness or grip to the roadway is increased, slipping to the subsoil is markedly reduced and returns almost to zero.
However, a slipping may occur between the tires and the inner side of the chain mesh (i.e., the side of the chain mesh facing towards the tire, which usually does not have any parts subject to wear). In the extreme case, such forces may occur that the chain links develop a shear action on the profile of the tires and the tires are damaged, which is a problem especially in the pure square chains.
Such a shear action is, of course, lowest in chains with round links. However, round links are also very movable in relation to one another, which leads to skewing of the chain links during driving and in case of higher loads, as a result of which the gripping action to the roadway is reduced—for example, because the parts subject to wear are no longer in optimal contact with the roadway.
In case of special square chains which have an angular profile on the outside and a round profile on the inside, there is a better gripping action with the roadway, since the edges of the square profile are interlocked with the tire profile on the outer side of the chain links and therefore contribute to an immediate transmission of forces from the tire to the subsoil. However, chains with such a special square profile have a certain flexibility due to the round profile design on the inner sides, such that the chain links tend to tilt and then, under a load, the chain slips over the tire surface. Then, this slipping may in turn lead to damage on the tire profile, but at any rate to additional wear. Moreover, the traction during driving is poor due to this skewing of the chain links as in the case of round link chains.
Square chains, which have an angular profile on the inside and outside, have a very low tendency to slip, since the chain links are not very movable in relation to one another as well as in relation to the tire profile. Such a chain proves to be a very stiff structure, whereby high forces occur between the chain links under a load, on the one hand, and, on the other hand, it threatens damage to the profile of the tire.